THE NEWARK SYSTEM OF NEW JERSEY 551 
which the materials may have been and probably were derived. 
In other cases, and this is true of the largest areas, the calcare- 
ous conglomerates abut against the gneissic rocks, and for much 
of this distance it is certain that no limestone occurs between the 
gneiss and conglomerate, at least not at the surface horizon. 
Gneissic pebbles, however, occur but rarely in the conglomerate. 
Substantially the same conditions prevail in the case of the 
quartzite conglomerate. For the most part it adjoins the gneiss, 
but gneissic pebbles in it are very rare. The known areas of 
quartzite from which the materials could have been derived are 
small, and in general not near the massive conglomerate beds. 
These facts can be explained on the hypothesis of a fault or 
series of faults along the northwestern border. But on the Del- 
aware River, at Monroe, Pa., the only locality along the border 
where even an approach to a good section was found, the con- 
glomerates seem rather to overlap the older rocks at a low 
angle, than to be faulted against them. In view of the contra- 
dictory nature of the evidence, the question of faults along this 
border is still an open one. 
The relation of the conglomerates to the shales is also an 
interesting and significant one. When traced along the strike 
the shales and argillites are found to grade into coarser beds which 
at some horizons become the massive conglomerates near the 
border. That this is the case has been established beyond a 
shadow of a doubt by numerous observations. Time and again 
thin pebbly layers were seen to appear in the shales and to 
increase in thickness and numbers until they became massive 
conglomerates. This is true both of the calcareous and of the 
quartzite conglomerates. 
These conglomerates do not, therefore, form a separate 
horizon but range through the whole formation. Those in the 
bluffs on the Delaware River above Milford belong with the Bruns- 
wick shales. So also do a part of those of the Barrens south- 
west of Pattenburg. Those of the Barrens north and northwest 
of Pittstown pass into the Lockatong beds and are therefore 
older than the conglomerates nearer the Delaware. The pebbly 
